RETURN VALUE

Returns 0 on success or negative on failure. If used in non-blocking mode, it
returns LIBSSH2_ERROR_EAGAIN when it would otherwise block. While
LIBSSH2_ERROR_EAGAIN is a negative number, it isn't really a failure per se.

ERRORS

LIBSSH2_ERROR_ALLOC - An internal memory allocation call failed.

LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.

LIBSSH2_ERROR_SOCKET_TIMEOUT -

LIBSSH2_ERROR_SFTP_PROTOCOL - An invalid SFTP protocol response was
received on the socket, or an SFTP operation caused an errorcode to be returned
by the server.